Inhibition of novel ß coronavirus replication by a combination of interferon-a2b and ribavirin

Falzarano, Darryl; de Wit, Emmie; Martellaro, Cynthia; Callison, Julie; Munster, Vincent J.; Feldmann, Heinz

Previous in vitro studies have demonstrated that SARS-CoV is sensitive to ribavirin 28 and to various classes of interferon (a, b and c) 27,29-34 . The sensitivity of SARS-CoV to ribavirin appears to be cell line dependent, with concentrations as low as 50 mg/ml ribavirin being reported as effective 16 . Unfortunately, this concentration is higher than the peak serum concentration reached in humans of approximately 24 mg/ml 35 . IFN-a2b was previously reported to inhibit growth of SARS-CoV starting at 1000 U/ml with a 1-log reduction at 2000 U/ml 34 . Following infection, only IFN-b (EC 50 560 IU/ml) has shown a dose dependent antiviral effect 36 . In this study we report a nearly 4-log reduction in virus titers for hCoV-EMC/2012 at comparable doses.